Process and apparatus for treating textile materials



May 4, 1965 c. A. AMOS ETAL PROCESS AND APPARATUS FOR TREATING TEXTILE MATERIALS Filed Oct. 26, 1962 FIG.1

I Em I FIG.2

INVENTORS CHARLES A. AMOS DANIEL J. LOVETT ATTORNEY United States Patent 3,181,967 PROCESS AND APPARATUS FOR TREATING TEXTILE MATERIALS Charles A. Amos and Daniel J. Lovett, Camden, S.C., assignors to E. I. du Pont de Nemonrs and Company, Wilmington, Del., a corporation of Delaware Filed Oct. 26, 1962, Ser. No. 233,256 3 Claims. (Cl. 117--67) This invention relates to apparatus and a process for uniformly applying aqueous conditioning agents to synthetic filaments which are in tow form.

In topical application of conditioning agents to synthetic filaments, it is generally highly desirable, and for some agents mandatory, to obtain uniform application along the length of all filaments in the tow. This is especially true of agents which are designed to alter the surface characteristics of the fiber in its ultimate use, such as, for example, durable antistatic agents or durable softening agents. The full benefit of such topically applied agents can only be realized with a uniform coating on all fiber surfaces.

Application of conditioning agents to continuous filament yarns of low total denier poses no great problem. Methods well known in the art can be employed to apply conditioning agents uniformly to all filaments in such structures. For example, such yarns can be drawn across a rotating roll which is partially immersed in the conditioning agent in such a manner as to contact all filaments by the film of finish retained by the roll, while the filaments are in the form of a fiat, monofilament-thick ribbon. Uniform application of conditioning agents to a tow comprising many thousands of filaments cannot generally be accomplished in this manner. It has been established that liquids, either aqueous or non-aqueous, usually can migrate to a uniform coating only along the surface of the filaments to which they have been applied. Little or no migration occurs fiber to fiber due to relatively infrequent contact of adjacent filaments with each other even in what appears to be a compact structure of parallel filaments.

An alternative method of application, that of complete immersion followed by expression of excess agent by passage between pressure rolls, has been tried. This method suffers from several disadvantages. If, as is frequently the case, the conditioning agent consists of more than a single, homogeneous, liquid phase, preferential wetting of the fiber by one of the phases may occur.

When this happens, the conditioning agent retained by the fiber after expression of excess by the pressure rolls may differ in composition from that of the bath as a whole. Furthermore, it frequently is not feasible to develop the optimum degree of fiber wettability in a liquid conditioning agent formulation which also provides the desired modification of fiber properties. Thus, even a complete immersion of the tow in the conditioning agent will not assure coating of all filaments in a tow in all cases.

The principal object of this invention is to provide a convenient and versatile apparatus and process for uniform treatment of a synthetic tow with a conditioning agent.

It is a further object to provide a process and apparatus for uniform treatment of substantially every filament in a synthetic tow with an aqueous conditioning agent which may contain a multiplicity of phases.

It is a still further object to provide a process and apparatus for uniform treatment of a filamentary tow with conditioning agents which avoid problems arising as a result of disproportionate application of complex mixtures of materials which differ in their ability to wet the filaments.

Other objects of this invention will appear hereinafter.

The objects of this invention are accomplished by passing a tow or web in .arcuate contact with a hollow, elongated guide having a narrow slot in its peripheral surface which extends across the Width of the tow. The guide directs the tow or web into brushing contact with the surface of a reservoir containing a liquid finish. Simultaneously, a predetermined amount of liquid finish is discharged through the slot onto the tow in a direction substantially perpendicular to the surface of the liquid in the reservoir. Surprisingly, very litle, if any, of the liquid finish is picked up from the reservoir; however, it is essential that contact be maintained with the surface of the liquid in order to ensure complete and uniform application of the liquid finish to all of the filaments in the tow.

This invention will be described in detail with reference to the accompanying drawings, in which:

FIGURE 1 is a schematic plan view of the apparatus of this invention, and

FIGURE 2 is an isometric drawing of the tow guide shown in FIGURE 1.

Referring to the drawings, a tow It is fed under tension from a supply source, not shown, in arcuate contact with a hollow, cylindrical guide 12 which has an elongated slot 14 extending longitudinally along its peripheral surface. As the tow 10 passes around guide 12, it is directed into brushing contact with the surface of the liquid in reservoir 16. Simultaneously a liquid finish is fed at a predetermined rate through inlet 18 and is discharged onto the tow Iii through slot 14. The tow 10, after passing around guide 12, is forwarded by pull rolls 2t) and 22 for further processing.

The liquid level in reservoir 16 is maintained at a predetermined level by positioing the reservoir so that outlet 24- is at the same level as the lower surface of tow 10 as it passes around guide 12. In order to maintain the predetermined liquid level in reservoir 16, the liquid finish may be pumped into reservoir 16 through inlet 26. The liquid may be permitted to continuously flow from reservoir 16 to outlet 24 and be recycled to inlet 26. Alternatively, known automatic liquid level control devices may be used to maintain the desired level.

Referring now specifically to FIGURE 2, the effective length of slot 14 may be varied by moving sealing collars 28 and 30 to various positions along guide 12 or by using sealing collars having various widths. After the width of the tow to be treated is determined, collars 28 and 30 are placed in position and then locked into position by screws 32 and 34.

In carrying out the process of the present invention, the tow should be in the form of a relatively flat web or ribbon of substantially uniform thickness. As the tow is brought into contact with the tow guide, it should approach and depart from the area of contact at an angle between 5 and The nature of the filamentary material and the particular liquid finish to be applied will determine the amount of finish to be metered onto the tow. Generally, the amount should be no greater than that which the tow can retain during subsequent passage between the pull rolls.

The dimensions of the slot through which the finish is discharged and the feed rate to the slot should be controlled to provide a velocity just suificient to permit penetration of the tow so that substantially all of the finish discharged onto the tow is absorbed during passage around the guide. After being treated with the liquid finish, the tow may be cut to staple, dried and packaged, or deposited on the bed of a continuous drier, dried and packaged as uncut tow.

As previously stated, penetration of the tow by the liquid finish or conditioning agent is essential in accomplishing the objects of this invention. Once the mini- Patented May 4, 1965 mum velocity for treatment of a particular product has been determined, the orifice width necessary to provide satisfactory penetration of the tow can be readily calculated. It has been found that a delivery velocity of 2.1 feet per second provides uniform penetration when using an aqueous finish having a viscosity in the range from about 1 to 2 centipoises on a 470,000-denier tow of 1.5 to 16.0 denier per filament acrylic fiber when the filaments are distributed uniformly along a 2 /2 inch width. Adjustments in the amount of conditioning agent applied may be accomplished by altering delivery rate of the conditioning agent if this can be done while maintaining the delivery velocity within satisfactory limits. Alternatively, adjustment in concentration of the conditioning agent in its aqueous suspension or solution may be employed. A velocity above the satisfactory limits can result in projection of conditioning agent into the bath with a consequent lowering of the desired level of application. This is particularly true of conditioning agents which do not rapidly wet the fiber. In such cases, a further disadvantage may be found in disproportionate application of conditioning agent components where the components do not have equal rates of fiber wetting. A velocity lower than the satisfactory velocity can result in inadequate penetration and thereby cause non-uniform application from fiber to fiber.

A slight contact of the lower side of the tow at the point of conditioning agent application with a pool of conditioning agent has been found necessary in order to provide a uniform coating on those fibers most remote from the slot. Without this contact, variable loss of conditioning agent by projection through the bundle can result from efforts to coat the most remote fibers. The fact that little or no conditioning agent is picked up from the pool is shown by a test in which a calculated level of 0.9% dry conditioning agent, delivered as an aqueous suspension through inlet 26, yielded an average dry application level of 0.88%, which duplicates the goal application within the limits of the analytical method employed. It has been found that a separate supply of finish to reservoir 16 can generally be substantially discontinued, once equilibrium conditions are established, without any net change in level of liquid therein. This further illustrates that control of liquid application is essentially dependent on the rate of metering through slot 14 of guide 12. Without the brushing contact with the pool of conditioning agent, however, non-uniform application of finish from fiber to fiber results as well as non-uniformity yard to yard along the length of the tow.

It has been found convenient to install this apparatus immediately upstream from a Beria-type cutter, em-

ploying the cutter feed rolls as the pull rolls 20 and 22. Excellent uniformity has been achieved either under conditions of constant tow travel, as in uniform chip length cutting, or under conditions of non-uniform rate of tow travel, as in variable chip length cutting. In the latter case, a conditioning agent metering pump must be operatively connected to the forwarding roll drive mechanism in order to provide a quantity of conditioning agent proportional to the speed of tow travel.

As many widely different embodiments of this invcntion may be made without departing from the spirit and scope thereof, it is to be understood that this invention is not to be limited to the specific embodiments thereof except as defined in the appended claims.

We claim:

1. Apparatus for applying a liquid to a moving filamentary tow comprising a liquid reservoir, means for maintaining a predetermined liquid level in said reservoir, and a hollow cylindrical guide positioned adjacent the surface of the liquid in said reservoir for directing said tow into brushing contact with said surface as said tow passes in contact with said guide, said guide having an inlet for receiving a liquid and an elongated slot extending longitudinally along its peripheral surface for discharging said liquid onto said tow in a direction substantially perpendicular to the surface of said liquid in said reservoir.

2. The apparatus of claim 1 having adjustable means for controlling the effective length of said elongated slot to accommodate tows of varying widths.

3. In a process for applying a uniform liquid finish to a moving filamentary tow, the steps of (a) passing said tow in arcuate contact with a hollow elongated guide having a narrow slot in the periphery thereof extending across the width of said tow, said tow being passed into contact with said guide at an angle between 5 and (b) simultaneously passing said tow in brushing contact with the surface of a reservoir containing liquid finish, and

(c) discharging a predetermined amount of liquid finish through said slot onto said tow in a direction substantially perpendicular to said surface.

References Cited by the Examiner UNITED STATES PATENTS 2,078,272 4/37 Novak 118-419 X 2,865,786 12/58 Turik 117-115 X 2,993,470 7/61 Stickel 118419 X RICHARD D. NEVIUS, Primary Examiner.

JOSEPH B. SPENCER, Examiner. 

3. IN A PROCESS FOR APPLYING A UNIFORM LIQUID FINISH TO A MOVING FILAMENTARY TOW, THE STEPS OF (A) PASSING SAID TOW IN ARCUATE CONTACT WITH A HOLLOW ELONGATED GUIDE HAVING A NARROW SLOT IN THE PERIPHERY THEREOF EXTENDING ACROSS THE WIDTH OF SAID TOW, SAID TOW BEING PASSED INTO CONTACT WITH SAID GUIDE AT AN ANGLE BETWEEN 5* AND 180*, (B) SIMULTANEOUSLY PASSING SAID TOW INBRUSHING CONTACT WITH THE SURFACE OF A RESERVOIR CONTAINING LIQUID FINISH, AND (C) DISCHARGING A PREDETERMINED AMOUNT OF LIQUID FINISH THROUGH SAID SLOT ONTO SAID TOW IN A DIRECTION SUBSTANTIALLY PERPENDICULAR TO SAID SURFACE. 